Storm season? 'Not looking good'

The hurricane season of 2005, which brought Hurricane Katrina, was possibly one of the most ill-predicted years on record.

In May that year, government forecasters said it would be an above-normal season, with 12 to 15 tropical storms. Seven to nine would become hurricanes, they said.

By the end of the season, 2005 was marked as the first season with 28 named storms, the first with 15 hurricanes and the first with four Category 5 hurricanes, the strongest ranking possible.

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The season shattered records and was the most devastating year for the United States in modern times, the administrator of the National Oceanic and Atmospheric Administration said at the time.

This week, NOAA predicted a season that may spawn as many as 23 named tropical storms, including up to seven major hurricanes. NOAA predicted that eight to 14 storms would strengthen into hurricanes, with top winds of 74 mph or higher. Three to seven of those could become major storms that reach Category 3 or higher - meaning they bring sustained winds of at least 111 mph.

Greg Holland, director of the earth systems laboratory at the National Center for Atmospheric Research in Boulder, Colo., has been studying hurricanes for 35 years.

"The season's not looking good," Holland said before the NOAA outlook was released Thursday.

He said predicting above-normal or below-normal seasons is about all that can be expected in any year. Beyond that, too many variables come into play that have an effect on how storms develop and act.

"Given 2004, we could have never predicted the 2005 season," he said.

That doesn't mean advances have not been made.

Better forecasting has been helped by advances in sensors that can be dropped into storms to scan conditions and by the availability of satellite images that add additional data.

Scientists have increasingly been able to predict hurricane tracks with greater accuracy but still have difficulty explaining sudden strengthening or weakening in storms, Holland said. Now, studies of the outer fringes of storms and their overall structure are providing information about why storm strengths shift. In the past, studies concentrated on the interior of the hurricane and its eye but revealed less.

"There will be a lot less surprises," he said.

Since the mid-1980s, hurricane predictions have gotten the biggest boost from a couple of things: a theory that was initially scoffed at and leaps in technology.

A lot of modern predictions rely on theories developed by William Gray, a meteorologist and professor at Colorado State University who issued his first forecast in 1984.

Now considered the dean of hurricane forecasting, his methods of making predictions by studying what happened in past seasons to deduce a theory flew in the face of the scientific method that said the theory should be developed first, then applied to the evidence.

"The scientific community was not kind to him," said Steve Letro, the meteorologist in charge of the National Weather Service office in Jacksonville. "They called it voodoo meteorology."

One discovery was that a weather condition called El Nino, which warms waters in the eastern Pacific, transfers that heat into thunderstorms that pump the warm air into the atmosphere where it travels across the Caribbean. If it collides with a developing hurricane in the eastern Atlantic, the moving warm air can shred the storm's top, causing it to fall apart.

Another condition, called a Bermuda High, is a clockwise rotation of air over the Atlantic that can steer hurricanes, sometimes to the south into the Gulf of Mexico, or spin them north toward the North Atlantic and Nova Scotia.

The position of the Bermuda High, which has other names, and its ability to redirect hurricanes is one factor that steers storms away from Northeast Florida, though it is not a fail-safe system. Close brushes are not uncommon. Once every three years, a storm center passes within 50 miles of Jacksonville, Letro said.

If the high is east of the coastline, a hurricane may begin to move northward, or "recurve" without touching land.

"Jacksonville is located pretty much at the latitude that storms, when they approach this area, are starting to turn northward," Letro said.

The high, however, is not stationary and can move east or west without much warning, he said.

Ten or 15 years ago, a forecast 24 hours ahead of landfall that was within a 90-mile range was considered fairly accurate, Letro said.

"The average 24-hour error for a hurricane forecast now is about 60 miles," he said.

Those kinds of improvements mean that this year warnings of approaching storms will come earlier, said First Coast News chief meteorologist Tim Deegan.

"Hurricane watches are coming out 48 hours in advance instead of 36," he said. Warnings, which were posted at 24 hours will now be announced at 36 hours.

Those changes are possible because of improvements in predicting a storm's path, Deegan said.

"The accuracy is increasing one to two miles a year," he said.

Holland, of the National Center for Atmospheric Research, said the most important tool for forecasters remains time. As the season progresses, it becomes easier to tell what is going to happen.

"You've got to wait for nature to get going, and nature is going now," he said.

dana.treen@jacksonville.com, (904) 359-4091

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